Liquid crystal device and method of driving the same

Abstract

A liquid crystal device comprising, at least, a liquid crystal element comprising at least a pair of substrates and a liquid crystal material disposed between the pair of electrodes, and electric field-applying means for applying an electric field to the liquid crystal element. The electric field-applying means applies a reverse electric field (−T INT ) so as to cancel an orientation energy difference (T INT ) depending upon relative directions between the applied electric field and aligned liquid crystal molecular axis in the liquid crystal element. There is provided a liquid crystal device capable of effectively suppressing the reduction in contrast, even when the optical response speed is increased.

1 . A liquid crystal device comprising: at least,
 a liquid crystal element capable of operated at high-speed; and electric field-applying means for applying an electric field to the liquid crystal element; the liquid crystal element comprising, at least, a pair of substrates, and a liquid crystal material disposed therebetween;   wherein the electric field-applying means is capable of applying an electric field (−T INT ) in a reverse direction so as to cancel a difference (T INT ) depending upon relative directions between the applied electric field and aligned liquid crystal molecular axis in the liquid crystal element.   
   
   
       2 . A liquid crystal device according to  claim 1 , wherein the electric field-applying means is capable of applying a reverse electric field in the vicinity of the initial alignment state under the absence of external electric field. 
   
   
       3 . A liquid crystal device according to  claim 1 , wherein the electric field-applying means is capable of controlling the rate of increase (dV/dt) in the reverse electric field with respect to time. 
   
   
       4 . A liquid crystal device according to  claim 1 , wherein the liquid crystal element is a liquid crystal element (PSS-LCD), which has a molecular initial alignment parallel or almost parallel to the alignment treatment direction for the liquid crystal material, and the liquid crystal material shows almost no spontaneous polarization which is perpendicular to the pair of substrates under the absence of an externally applied voltage. 
   
   
       5 . A liquid crystal device according to  claim 4 , wherein the orientation energy difference (T INT ) depending upon relative directions between the applied electric field and aligned liquid crystal molecular axis in the liquid crystal element is equal to an orientation energy difference which is generated due to the coupling of a quadrupole moment and an internal electric field in the liquid crystal element. 
   
   
       6 . A liquid crystal device according to  claim 1 , wherein the electric field-applying means comprises, at least:
 a response speed analyzer for analyzing an electro-optical response speed of the liquid crystal element by utilizing transmitted light having passed through the liquid crystal element; and   an electric field application regulator for regulating a voltage to be applied to the liquid crystal element in response to a signal from the response speed analyzer.   
   
   
       7 . A liquid crystal device according to  claim 1 , wherein the response speed analyzer comprises, at least, light-receiving means for measuring transmitted light having passed through the liquid crystal element. 
   
   
       8 . A liquid crystal device according to  claim 1 , wherein the electric field application regulator comprises, at least, a waveform generator for generating a voltage to be applied to the liquid crystal element. 
   
   
       9 . A liquid crystal device according to  claim 7 , which further comprises a temperature controller for controlling the temperature of the light-receiving means. 
   
   
       10 . A method of driving a liquid crystal device comprising, at least, a liquid crystal element and electric field-applying means for applying an electric field to the liquid crystal element; the liquid crystal element comprising, at least, a pair of substrates and a liquid crystal material disposed between the pair of electrodes;
 wherein a reverse electric field (−T INT ) is applied from the electric field-applying means to the liquid crystal element, so as to cancel an orientation energy difference (T INT ) depending upon relative directions between the applied electric field and aligned liquid crystal molecular axis in the liquid crystal element.   
   
   
       11 . A method of driving a liquid crystal device according to  claim 10 , wherein the orientation energy difference is canceled by applying a reverse electric field from the electric field-applying means in the vicinity of initial alignment state under the absence of external electric field. 
   
   
       12 . A method of driving a liquid crystal device according to  claim 10 , wherein the orientation energy difference is canceled by controlling the rate of increase in the reverse electric field with respect to time (dV/dt) in the application of an electric field from the electric field-applying means.